Blepharitis, an inflammation of the edge of the eyelid, is a common clinical problem. Blepharitis occurs as an ulcerous (staph) form or nonulcerous (seborrheic) form, or as a combination of both forms. Mixed blepharitis is seborrheic with associated staph. Patients who suffer from blepharitis as a result of an ocular demodex infestation often present with a number of symptoms such as a foreign body sensation, redness and itching. The symptoms can become severe enough that the patient may require surgery to achieve relief. However, even invasive treatments such as surgery often result in no significant improvement, and/or a recurrence of the demodex infestation.
Demodex mites, Class Arachnid and Order Acarina, are elongated ectoparasites. Among a wide range of reported species, only two, demodex folliculorum (D. folliculorum) and demodex brevis (D. brevis), are found on the human body surface. Adult D. folliculorum is commonly found in small hair follicles. D. brevis burrows deeper into the eyelash sebaceous gland and the meibomian gland. Both demodex species often coexist at the same skin area and tend to gather in the face, cheeks, the forehead, the nose, and the external ear tract, where active sebum excretion favors their habitat and breeding.
Acarine arachnids such as the demodex mite, demodex folliculorum, also can infest mammalian quadrupeds, in particular domestic animals, especially dogs, causing demodetic mange. The demodex mite burrows into hair follicles and sebaceous glands of the animal, the mite often causing severe dermatitis, infection, and discomfort. Demodetic mange, particularly in dogs, presents a difficult clinical problem for veterinarians, as it can involve the face and the entire body of the animal in some cases. Existing treatments can be expensive and are not always effective, with the result that affected animals are sometimes euthanized.
Mange can also be caused by the burrowing parasitic mites Sarcoptes, which causes scabies, and Chorioptes. The Cheyletiella mite causes a condition known as “walking dandruff” In cats, notoedric mange is a burrowing mite infestation that is difficult to treat.
In general, parasitic mites such as those causing mange are transmissible to humans.
Generally, demodex is currently treated with both systemic and topical administration of parasiticides. For example, ocular demodex in humans is treated by daily practice of eyelid margin scrub with diluted shampoo alone or combined with 1% mercury oxide ointment, 2% metronidazoles gel or Pilocarpine gel at the base of the eye lashes at the night time. Ophthalmic reports demonstrated a dramatic decrease in the demodex count observed during the follow-up examination.
However, to date, no report has demonstrated that these treatments actually kill demodex in vitro and no therapeutic agent has completely eradicated ocular demodex within one month. Indeed, recent investigations revealed that ocular demodex persists in 50% of patients even after one year of lid scrub with ordinary, diluted shampoo alone or combined with 1% mercury oxide ointment, 2% metronidazoles gel or Pilocarpine gel.
Rosacea is a chronic dermatological disease that affects the skin, usually the face, and sometimes the eyes. Only rarely are other parts of the upper body affected. One type of rosacea, inflammatory rosacea, causes persistent redness and pink bumps referred to as papules, and pustules on the skin. Eye inflammation also may occur, with symptoms often including sensitivity to light, blurred or otherwise impaired vision, redness, dryness, itching, burning, tearing, and the sensation of having grit or sand in the eye. The eyelids may become inflamed and swollen. “Rosacea”, as the term is used herein, refers to both “rosacea of the skin” and to “ocular rosacea”.
In an advanced stage of rosacea, inflammation of the eye is more apparent, and the skin thickens and becomes a deep shade of red. Rosacea is difficult to treat. Current treatments include oral antibiotics, e.g., tetracycline or doxycycline. If infections of the eyelids develop, physicians may recommend scrubbing the eyelids with diluted baby shampoo. Steroid eye drops may be prescribed in the case of severe infection.
Acne, including acne vulgaris and acne rosacea, is yet another chronic dermatological condition that is difficult to treat. Over-the-counter products for treatment of acne, including benzoyl peroxide and aluminium chlorhydroxide/sulphur can help reduce, but not cure acne. Prescription treatments, including antibiotics, retinoids, and certain hormone pills, can improve acne, but can have serious adverse effects.
Thus, a need exists for improved methods of treating ocular demodex, and demodex-induced blepharitis and rosacea. In addition, there is an ongoing need for improved treatments for the ocular condition described as meibomian gland dysfunction and for the dermatological conditions of acne and rosacea.